In the recent past, industry has been faced with the problem presented by the sensitivity of modern electronic circuits to static electricity. This is particularly true of printed circuit boards and the like that use integrated circuits. These circuits can be completely destroyed by being subject to static electricity. As is well known, such static electricity can reach 20,000 volts in the common situation of a human being walking across a carpeted room. It is, therefore, important that containers or packages be provided to retain these static-sensitive articles in such a way that they are insulated against static electricity. For this purpose, a number of techniques have been used, usually involving layers of conductive materials such as foil and the like that are incorporated into the packages to surround the articles, so that the static electricity is drained away. In order to maintain the cost of such containers at a low value, it has become common practice to use carbon layers for this purpose, the carbon layer being printed on the material from which the container is made. Since corrugated board is the material from which most inexpensive containers are made, it has become common practice to coat a surface of the board with the carbon layer. There are a number of difficulties experienced with that process, one of which is that the carbon layer would normally be applied in the factory which makes the corrugated board. The corrugated board is then shipped to a converter who makes it into various types of containers. It can be seen, then, that the handling of the board between the manufacturing plant and the converters plant could result in destruction of this layer of carbon. Also, once the container is made, the carbon layer is exposed to the action of the static-sensitive article during shipment and the like, and particles of the carbon can become dislodged and land in a critical area on an integrated circuit for instance, on an I.C. chip. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a container for static-sensitive articles in which a static barrier is incorporated in a corrugated board wall in such a way that it is not exposed on an exterior surface.
Another object of this invention is the provision of a container having a static barrier in which particles of carbon can not be loosened and come in contact with static-sensitive articles contained therein.
A further object of the present invention is the provision of a corrugated board for a static-shielded container, which board has a carbon layer incorporated in the interior during manufacture, so that handling in transportation from the board manufacturer to the converter can not damage the layer.
It is another object of the instant invention to provide a container for use with static-sensitive articles which is simple in construction, which is inexpensive to manufacture, and which is capable of extensive use without damage or deterioration of the static electricity shielding capability.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.